%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  This file is part of Logtalk <https://logtalk.org/>
%  SPDX-FileCopyrightText: 1998-2025 Paulo Moura <pmoura@logtalk.org>
%  SPDX-License-Identifier: Apache-2.0
%
%  Licensed under the Apache License, Version 2.0 (the "License");
%  you may not use this file except in compliance with the License.
%  You may obtain a copy of the License at
%
%      http://www.apache.org/licenses/LICENSE-2.0
%
%  Unless required by applicable law or agreed to in writing, software
%  distributed under the License is distributed on an "AS IS" BASIS,
%  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%  See the License for the specific language governing permissions and
%  limitations under the License.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


:- object(grammar_rules_hook,
	implements(expanding)).

	:- info([
		version is 1:0:0,
		author is 'Paulo Moura',
		date is 2020-02-14,
		comment is 'This hook object expands grammar rules into clauses.',
		see_also is [
			backend_adapter_hook, default_workflow_hook,
			identity_hook, prolog_module_hook(_), object_wrapper_hook,
			write_to_stream_hook(_, _), write_to_stream_hook(_),
			print_goal_hook, suppress_goal_hook
		]
	]).

	term_expansion((GRHead --> GRBody), Clause) :-
		{	'$lgt_comp_ctx_mode'(CompilationContext, runtime),
			'$lgt_dcg_rule'((GRHead --> GRBody), Clause0, CompilationContext),
			(	Clause0 = (Head :- Body0) ->
				'$lgt_simplify_goal'(Body0, Body),
				(	Body == true ->
					Clause = Head
				;	Clause = (Head :- Body)
				)
			;	Clause = Clause0
			)
		}.

:- end_object.
